1. Field of the Invention
The present invention relates to manually shifted range-type compound transmissions having enhanced automatic range shifting mechanisms and controls. In particular, the present invention relates to manually shifted range-type transmissions of the "H 1/2 " or "double-H" type having an "autorange" type shift mechanism of the general kind disclosed in U.S. Pat. Nos. 3,492,202; 4,275,612; 4,455,883; 5,000,060 and 5,193,410, the disclosures of which are incorporated herein by reference, wherein the range shift controller will prevent range shifting at vehicle speeds at which such shifting is predetermined to be inappropriate.
2.DESCRIPTION OF THE PRIOR ART
Change-gear transmissions of the range type and of the combined range-and-splitter type are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 4,455,883; 4,754,665; 5,193,410; 5,000,060 and 5,390,561, the disclosures of which are incorporated herein by reference. Range-type transmissions having shift controls of the "multiple-H" type, as opposed to the "repeat-H" type, which utilize an automatic range shift mechanism responsive to movement of a shift lever from a first to a second area or portion of the shift pattern, are well known, as may be seen by reference to aforementioned U.S. Pat. Nos. 4,455,883; 4,974,468; 5,000,060 and 5,193,410.
While the prior art manually shifted, range-type transmissions utilizing automatic range shifting controls are widely used and commercially successful, they are not totally satisfactory, as, due to error or inattention, an operator may select a range shift inappropriate under current vehicle speed conditions, which shift will be automatically completed by the range actuator and usual synchronized range clutch assembly.